Fuel-air mixer assembly for use in a combustor of a turbine engine

ABSTRACT

A fuel-air mixer assembly that includes a mixer portion, and a flare cup portion coupled to the mixer portion. The flare cup portion includes a side wall that including an inlet opening and a discharge opening defined therein. The side wall is oriented such that the discharge opening is axi-asymmetrically shaped relative to a centerline of the fuel-air mixer assembly.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH & DEVELOPMENT

This invention was made with Government support under contract numberFA8650-09-D-2922 awarded by the Department of the Air Force. TheGovernment has certain rights in this invention.

BACKGROUND

The present disclosure relates generally to turbine engines and, morespecifically, to a fuel-air mixer assembly having axi-asymmetriccharacteristics for reducing combustion dynamics.

A combustion section of a gas turbine generally includes a plurality ofcombustors that are arranged in an annular array about an outer casing,such as a compressor discharge casing. Pressurized air flows from acompressor towards the compressor discharge casing, and is thenchanneled to each combustor. Fuel from a fuel nozzle is mixed with thepressurized air in each combustor to form a combustible mixture within aprimary combustion zone of the combustor. The combustible mixture isburned to produce hot combustion gases having a high pressure and highvelocity. In at least some known combustors, high combustion dynamicsare formed when the combustible mixture is burned. High combustiondynamics adversely affect the operability and service life of thecombustors. Moreover, high combustion dynamics can result in damage tocomponents of the combustors, thereby causing service outages andincreasing repair costs.

BRIEF DESCRIPTION

In one aspect, a fuel-air mixer assembly for use in a combustor isprovided. The fuel-air mixer assembly includes a mixer portion, and aflare cup portion coupled to the mixer portion. The flare cup portionincludes a side wall that including an inlet opening and a dischargeopening defined therein. The side wall is oriented such that thedischarge opening is axi-asymmetrically shaped relative to a centerlineof the fuel-air mixer assembly.

In another aspect, a combustor for use in a turbine engine is provided.The combustor includes a fuel nozzle assembly, and a fuel-air mixerassembly including a mixer portion configured to receive fuel from thefuel nozzle assembly. The fuel-air mixer assembly also includes a flarecup portion coupled to the mixer portion. The flare cup portion includesa side wall that including an inlet opening and a discharge openingdefined therein. The side wall is oriented such that the dischargeopening is axi-asymmetrically shaped relative to a centerline of thefuel-air mixer assembly.

In yet another aspect, a turbine engine is provided. The turbine engineincludes a combustor including a fuel nozzle assembly and a fuel-airmixer assembly coupled to the fuel nozzle assembly. The fuel-air mixerassembly includes a mixer portion configured to receive fuel from thefuel nozzle assembly, and a flare cup portion coupled to the mixerportion. The flare cup portion includes a side wall that including aninlet opening and a discharge opening defined therein. The side wall isoriented such that the discharge opening is axi-asymmetrically shapedrelative to a centerline of the fuel-air mixer assembly.

DRAWINGS

These and other features, aspects, and advantages of the presentdisclosure will become better understood when the following detaileddescription is read with reference to the accompanying drawings in whichlike characters represent like parts throughout the drawings, wherein:

FIG. 1 is a schematic diagram of an exemplary turbine engine;

FIG. 2 is a cross-sectional view of a portion of an exemplary combustorthat may be used with the turbine engine shown in FIG. 1;

FIG. 3 is a cross-sectional view of an exemplary fuel-air mixer assemblythat may be used in the combustor shown in FIG. 2;

FIG. 4 is an axial view of the fuel-air mixer assembly shown in FIG. 3;

FIG. 5 is a cross-sectional view of an alternative fuel-air mixerassembly that may be used in the combustor shown in FIG. 2;

FIG. 6 is an axial view of the fuel-air mixer assembly shown in FIG. 5;and

FIG. 7 is an axial view of an exemplary swirler vane assembly that maybe used in the fuel-air mixer assemblies shown in FIGS. 3 and 5.

Unless otherwise indicated, the drawings provided herein are meant toillustrate features of embodiments of the disclosure. These features arebelieved to be applicable in a wide variety of systems comprising one ormore embodiments of the disclosure. As such, the drawings are not meantto include all conventional features known by those of ordinary skill inthe art to be required for the practice of the embodiments disclosedherein.

DETAILED DESCRIPTION

In the following specification and the claims, reference will be made toa number of terms, which shall be defined to have the followingmeanings.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

“Optional” or “optionally” means that the subsequently described eventor circumstance may or may not occur, and that the description includesinstances where the event occurs and instances where it does not.

Approximating language, as used herein throughout the specification andclaims, may be applied to modify any quantitative representation thatcould permissibly vary without resulting in a change in the basicfunction to which it is related. Accordingly, a value modified by a termor terms, such as “about”, “approximately”, and “substantially”, are notto be limited to the precise value specified. In at least someinstances, the approximating language may correspond to the precision ofan instrument for measuring the value. Here and throughout thespecification and claims, range limitations may be combined and/orinterchanged. Such ranges are identified and include all the sub-rangescontained therein unless context or language indicates otherwise.

As used herein, the terms “axial” and “axially” refer to directions andorientations that extend substantially parallel to a centerline of theturbine engine or the combustor. Moreover, the terms “radial” and“radially” refer to directions and orientations that extendsubstantially perpendicular to the centerline of the turbine engine orthe fuel-air mixer assembly. In addition, as used herein, the terms“circumferential” and “circumferentially” refer to directions andorientations that extend arcuately about the centerline of the turbineengine or the fuel-air mixer assembly.

Embodiments of the present disclosure relate to a fuel-air mixerassembly having axi-asymmetric characteristics for reducing combustiondynamics. More specifically, the fuel-air mixer assembly includes one ormore design features of a mixer portion, a flare cup portion, or aferrule portion of the assembly that are implemented, either alone or incombination, to reduce combustion dynamics by disrupting symmetrieswithin the assembly. For example, at least one of the orientation,shape, and/or design of swirler vanes within the mixer portion, inletsand outlets of the flare cup portion, and purge holes within the ferruleportion are formed axi-asymmetrically relative to a centerline of acombustor to facilitate disrupting a swirling flow of fuel and airdischarged from the fuel-air mixer assembly. As such, combustiondynamics are reduced in a simplified and efficient manner.

FIG. 1 is a schematic diagram of an exemplary turbine engine 10including a fan assembly 12, a low-pressure or booster compressorassembly 14, a high-pressure compressor assembly 16, and a combustorassembly 18. Fan assembly 12, booster compressor assembly 14,high-pressure compressor assembly 16, and combustor assembly 18 arecoupled in flow communication. Turbine engine 10 also includes ahigh-pressure turbine assembly 20 coupled in flow communication withcombustor assembly 18 and a low-pressure turbine assembly 22. Fanassembly 12 includes an array of fan blades 24 extending radiallyoutward from a rotor disk 26. Low-pressure turbine assembly 22 iscoupled to fan assembly 12 and booster compressor assembly 14 through afirst drive shaft 28, and high-pressure turbine assembly 20 is coupledto high-pressure compressor assembly 16 through a second drive shaft 30.Turbine engine 10 has an intake 32 and an exhaust 34. Turbine engine 10further includes a centerline 36 about which fan assembly 12, boostercompressor assembly 14, high-pressure compressor assembly 16, andturbine assemblies 20 and 22 rotate.

In operation, air entering turbine engine 10 through intake 32 ischanneled through fan assembly 12 towards booster compressor assembly14. Compressed air is discharged from booster compressor assembly 14towards high-pressure compressor assembly 16. Highly compressed air ischanneled from high-pressure compressor assembly 16 towards combustorassembly 18, mixed with fuel, and the mixture is combusted withincombustor assembly 18. High temperature combustion gas generated bycombustor assembly 18 is channeled towards turbine assemblies 20 and 22.Combustion gas is subsequently discharged from turbine engine 10 viaexhaust 34.

FIG. 2 is a cross-sectional view of a portion of an exemplary combustor38 that may be used with turbine engine 10. Combustor 38 defines acombustion chamber 40 in which the highly compressed air is mixed withfuel and combusted. Combustor 38 includes an outer liner 42 and an innerliner 44. Outer liner 42 defines an outer boundary of the combustionchamber 40, and inner liner 44 defines an inner boundary of combustionchamber 40. An annular dome 46 is mounted upstream from outer liner 42and inner liner 44 defines an upstream end of combustion chamber 40. Oneor more fuel injection systems 48 are positioned on annular dome 46. Inthe exemplary embodiment, each fuel injection system 48 includes a fuelnozzle assembly 50 and a fuel-air mixer assembly 52 coupled to fuelnozzle assembly 50. Fuel-air mixer assembly 52 receives fuel from fuelnozzle assembly 50, receives air from high-pressure compressor assembly16 (shown in FIG. 1) via a diffuser 54, and discharges a fuel-airmixture 56 into combustion chamber 40.

FIG. 3 is a cross-sectional view of fuel-air mixer assembly 52 that maybe used in combustor 38 (shown in FIG. 2), and FIG. 4 is an axial viewof fuel-air mixer assembly 52. In the exemplary embodiment, fuel-airmixer assembly 52 includes a mixer portion 58 and a flare cup portion 60coupled to mixer portion 58. Mixer portion 58 includes a first radialflow passage 62 and a second radial flow passage 64 each having aswirler vane assembly 66 positioned therein, as will be described inmore detail below. Flare cup portion 60 includes a side wall 68 that hasan inlet opening 70 and a discharge opening 72 defined therein. Sidewall 68 is oriented such that discharge opening 72 is axi-asymmetricallyshaped relative to a centerline 74 of fuel-air mixer assembly 52. Asdescribed above, fuel-air mixture 56 (shown in FIG. 2) is dischargedfrom fuel-air mixer assembly 52 during operation of combustor 38. Morespecifically, fuel-air mixture 56 generally swirls circumferentiallyabout centerline 74 before being discharged from fuel-air mixer assembly52. As such, shaping discharge opening 72 axi-asymmetrically relative tocenterline 74 facilitates disrupting a symmetrical flow field offuel-air mixture 56 before being discharged from fuel-air mixer assembly52.

For example, referring to FIG. 4, discharge opening 72 is defined by amajor axis 76 and a minor axis 78 oriented perpendicularly relative toeach other. Discharge opening 72 is shaped axi-asymmetrically in thatmajor axis 76 is longer than minor axis 78. Moreover, fuel-air mixerassembly 52 is oriented within combustor 38 (shown in FIG. 2) such thatmajor axis 76 is oriented tangentially relative to a circumference ofturbine engine 10 (shown in FIG. 1). As such, flame propagation isenhanced and impingement of fuel-air mixture 56 and heat against outerliner and inner liner 44 (shown in FIG. 2) is reduced.

Referring again to FIG. 3, side wall 68 of flare cup portion 60 isdivergently oriented relative to centerline 74 of fuel-air mixerassembly 52 at opposing ends of major axis 76 and minor axis 78. Assuch, side wall 68 is angled relative to centerline 74 at the opposingends of major axis 76 and minor axis 78 by any angle that enables flarecup portion 60 to function as described herein. In the exemplaryembodiment, side wall 68 at opposing ends of major axis 76 is orientedat an angle θ equal to or less than about 60 degrees relative tocenterline 74. Moreover, side wall 68 at opposing ends of minor axis 78is oriented at an angle less than angle θ such that a planar opening isformed at discharge opening 72.

In the exemplary embodiment, mixer portion 58 includes a discharge end80 coupled to flare cup portion 60 at inlet opening 70. In operation,fuel and air are mixed within mixer portion 58 and discharged from mixerportion 58 through an outlet 82 defined at discharge end 80. Inaddition, air enters mixer portion 58 radially and is discharged frommixer portion 58 through an annular opening 84 defined at discharge end80. Outlet 82 is defined by a first side wall 86 and annular opening 84is defined by a second side wall 88. In one embodiment, first side wall86 and second side wall 88 are both shaped axi-symmetrically relative tocenterline 74. Likewise, side wall 68 of flare cup portion 60 at inletopening 70 is shaped axi-symmetrically relative to centerline 74. Assuch, flare cup portion 60 is retrofittable onto an existing cylindricaldischarge end 80 of mixer portion 58.

Fuel-air mixer assembly 52 also includes a ferrule portion 90 coupled tomixer portion 58. Ferrule portion 90 includes a fuel inlet 92 and aplurality of purge holes defined therein. The plurality of purge holesdirect axial airflow into mixer portion 58. In addition, the pluralityof purge holes include first purge holes 94 and second purge holes 96defined in ferrule portion 90 and arranged circumferentially relative tocenterline 74. First purge holes 94 are sized smaller than second purgeholes 96. More specifically, first purge holes 94 and second purge holes96 are arranged axi-asymmetrically based on the size of first purgeholes 94 and second purge holes 96 relative to centerline 74. In theexemplary embodiment, sets of first purge holes 94 and sets of secondpurge holes 96 are alternatingly arranged relative to centerline 74.Alternatively, first purge holes 94 and second purge holes 96 areindividually alternatingly arranged relative to centerline 74.

In the exemplary embodiment, flare cup portion 60 includes a transitionsection 93 defined between a cylindrical section 95 and a flared section97 of flare cup portion 60. Transition section 93 has any shape thatenables fuel-air mixer assembly 52 to function as described herein. Forexample, transition section 93 may be defined by a sharp corner or havea radius of less than or equal to about 0.15 inches. In addition, flaredsection 97 has either a flat surface or a curved surface. When curved,flared section 97 curves outwardly relative to centerline 74 fromtransition section 93 by an angular increase of less than or equal toabout 50 degrees.

FIG. 5 is a cross-sectional view of an alternative fuel-air mixerassembly 98 that may be used in combustor 38 (shown in FIG. 2), and FIG.6 is an axial view of fuel-air mixer assembly 98. In the exemplaryembodiment, mixer portion 58 includes a discharge end 100 coupled toflare cup portion 60 at an inlet opening 102. In operation, fuel and airare mixed within mixer portion 58 and discharged from mixer portion 58through an outlet 104 defined at discharge end 100. In addition, airenters mixer portion 58 radially and is discharged from mixer portion 58through an annular opening 106 defined at discharge end 100. Outlet 104is defined by first side wall 86 and annular opening 106 is defined bysecond side wall 88. In one embodiment, first side wall 86 and secondside wall 88 are both shaped axi-asymmetrically relative to centerline74. Likewise, side wall 68 of flare cup portion 60 at inlet opening 102is shaped axi-asymmetrically relative to centerline 74 to facilitatecoupling between mixer portion 58 and flare cup portion 60.Axi-asymmetrically shaping outlet 104 and annular opening 106 furtherfacilitates disrupting a symmetrical flow field of fuel-air mixture 56(shown in FIG. 2) before being discharged from fuel-air mixer assembly52.

FIG. 7 is an axial view of an exemplary swirler vane assembly 66 thatmay be used in mixer portion 58 of fuel-air mixer assemblies 52 and 98(shown in FIGS. 3 and 5). In the exemplary embodiment, swirler vaneassembly 66 includes first swirler vanes 108 and second swirler vanes110 arranged circumferentially within mixer portion 58 relative tocenterline 74. First swirler vanes 108 direct airflow into mixer portion58 in a different direction than second swirler vanes 110. Morespecifically, first swirler vanes 108 and second swirler vanes 110 areangled differently relative to a radial axis 112 of fuel-air mixerassembly 52. For example, an angle α defined between radial axis 112 andfirst swirler vanes 108 is less than an angle β defined between radialaxis 112 and second swirler vanes 110. In the exemplary embodiment, setsof first swirler vanes 108 and sets of second swirler vanes 110 arealternatingly arranged relative to centerline 74 (shown in FIG. 3).Alternatively, first swirler vanes 108 and second swirler vanes 110 areindividually alternatingly arranged relative to centerline 74.

An exemplary technical effect of the systems and methods describedherein includes at least one of: (a) improving combustion dynamics in acombustor of a turbine engine; (b) forming a fuel-air mixer assemblywith axi-asymmetric design features; and (c) improving the service lifeand operability of the turbine engine.

Exemplary embodiments of a turbine engine and related components aredescribed above in detail. The system is not limited to the specificembodiments described herein, but rather, components of systems and/orsteps of the methods may be utilized independently and separately fromother components and/or steps described herein. For example, theconfiguration of components described herein may also be used incombination with other processes, and is not limited to practice withonly turbofan assemblies and related methods as described herein.Rather, the exemplary embodiment can be implemented and utilized inconnection with many applications where reducing combustion dynamics isdesired.

Although specific features of various embodiments of the presentdisclosure may be shown in some drawings and not in others, this is forconvenience only. In accordance with the principles of embodiments ofthe present disclosure, any feature of a drawing may be referencedand/or claimed in combination with any feature of any other drawing.

This written description uses examples to disclose the embodiments ofthe present disclosure, including the best mode, and also to enable anyperson skilled in the art to practice embodiments of the presentdisclosure, including making and using any devices or systems andperforming any incorporated methods. The patentable scope of theembodiments described herein is defined by the claims, and may includeother examples that occur to those skilled in the art. Such otherexamples are intended to be within the scope of the claims if they havestructural elements that do not differ from the literal language of theclaims, or if they include equivalent structural elements withinsubstantial differences from the literal languages of the claims.

What is claimed is:
 1. A fuel-air mixer assembly for use in a combustor,said fuel-air mixer assembly comprising: a mixer portion; and a flarecup portion coupled to said mixer portion, said flare cup portioncomprising a side wall that comprises an inlet opening and a dischargeopening defined therein, wherein said side wall is oriented such thatsaid discharge opening is axi-asymmetrically shaped relative to acenterline of the fuel-air mixer assembly.
 2. The assembly in accordancewith claim 1, wherein said discharge opening is defined by a major axisand a minor axis oriented perpendicularly relative to each other, themajor axis longer than the minor axis.
 3. The assembly in accordancewith claim 2, wherein said side wall is divergently oriented relative tothe centerline of the fuel-air mixer assembly at opposing ends of themajor axis, said side wall oriented at an angle equal to or less thanabout 60 degrees relative to the centerline.
 4. The assembly inaccordance with claim 1, wherein said mixer portion comprises adischarge end coupled to said flare cup portion at said inlet opening,said inlet opening and said discharge end both axi-symmetrically shapedrelative to the centerline of the fuel-air mixer assembly.
 5. Theassembly in accordance with claim 1, wherein said mixer portioncomprises a discharge end coupled to said flare cup portion at saidinlet opening, said inlet opening and said discharge end bothaxi-asymmetrically shaped relative to the centerline of the fuel-airmixer assembly.
 6. The assembly in accordance with claim 1, wherein saidmixer portion comprises first swirler vanes and second swirler vanesarranged circumferentially within said mixer portion relative to thecenterline, wherein said first swirler vanes are configured to directairflow into said mixer portion in a different direction than saidsecond swirler vanes.
 7. The assembly in accordance with claim 1 furthercomprising a ferrule portion coupled to said mixer portion, said ferruleportion comprising first purge holes and second purge holes definedtherein and arranged circumferentially relative to the centerline,wherein said first purge holes are sized smaller than said second purgeholes.
 8. The assembly in accordance with claim 1, wherein said flarecup portion comprises a cylindrical section, a flared section, and atransition section defined therebetween.
 9. A combustor for use in aturbine engine, said combustor comprising: a fuel nozzle assembly; and afuel-air mixer assembly comprising: a mixer portion configured toreceive fuel from said fuel nozzle assembly; and a flare cup portioncoupled to said mixer portion, said flare cup portion comprising a sidewall that comprises an inlet opening and a discharge opening definedtherein, wherein said side wall is oriented such that said dischargeopening is axi-asymmetrically shaped relative to a centerline of saidfuel-air mixer assembly.
 10. The combustor in accordance with claim 9,wherein said discharge opening is defined by a major axis and a minoraxis oriented perpendicularly relative to each other, the major axislonger than the minor axis.
 11. The combustor in accordance with claim10, wherein said fuel-air mixer assembly is oriented within thecombustor such that the major axis is oriented tangentially relative toa circumference of the turbine engine.
 12. The combustor in accordancewith claim 10, wherein said side wall is divergently oriented relativeto the centerline of said fuel-air mixer assembly at opposing ends ofthe major axis, said side wall oriented at an angle equal to or lessthan about 60 degrees relative to the centerline.
 13. The combustor inaccordance with claim 9, wherein said mixer portion comprises adischarge end coupled to said flare cup portion at said inlet opening,said inlet opening and said discharge end both axi-symmetrically shapedrelative to the centerline of said fuel-air mixer assembly.
 14. Thecombustor in accordance with claim 9, wherein said mixer portioncomprises a discharge end coupled to said flare cup portion at saidinlet opening, said inlet opening and said discharge end bothaxi-asymmetrically shaped relative to the centerline of said fuel-airmixer assembly.
 15. The combustor in accordance with claim 9, whereinsaid mixer portion comprises first swirler vanes and second swirlervanes arranged circumferentially within said mixer portion relative tothe centerline, wherein said first swirler vanes are configured todirect airflow into said mixer portion in a different direction thansaid second swirler vanes.
 16. A turbine engine comprising: a combustorcomprising a fuel nozzle assembly and a fuel-air mixer assembly coupledto said fuel nozzle assembly, said fuel-air mixer assembly comprising: amixer portion configured to receive fuel from said fuel nozzle assembly;and a flare cup portion coupled to said mixer portion, said flare cupportion comprising a side wall that comprises an inlet opening and adischarge opening defined therein, wherein said side wall is orientedsuch that said discharge opening is axi-asymmetrically shaped relativeto a centerline of said fuel-air mixer assembly.
 17. The turbine enginein accordance with claim 16, wherein said discharge opening is definedby a major axis and a minor axis oriented perpendicularly relative toeach other, the major axis longer than the minor axis.
 18. The turbineengine in accordance with claim 17, wherein said side wall isdivergently oriented relative to the centerline of said fuel-air mixerassembly at opposing ends of the major axis, said side wall oriented atan angle equal to or less than about 60 degrees relative to thecenterline.
 19. The turbine engine in accordance with claim 16, whereinsaid mixer portion comprises first swirler vanes and second swirlervanes arranged circumferentially within said mixer portion relative tothe centerline, wherein said first swirler vanes are configured todirect airflow into said mixer portion in a different direction thansaid second swirler vanes.
 20. The turbine engine in accordance withclaim 16 further comprising a ferrule portion coupled to said mixerportion, said ferrule portion comprising first purge holes and secondpurge holes defined therein and arranged circumferentially relative tothe centerline, wherein said first purge holes are sized differentlythan said second purge holes.